Senate Democrats broadened their assault on unrestricted political money Tuesday, introducing a campaign finance disclosure bill that its authors said will be voted on this year.

Senate Majority Leader Harry Reid had already promised a vote on a constitutional amendment that would let Congress and the states curb political spending. Democrats now plan to also vote on the disclosure bill known as the DISCLOSE Act, which Republicans blocked via filibuster in 2010 and 2012.

“Since the Supreme Court’s disastrous Citizens United decision, a torrent of dark money has swept through our political system, giving corporations and billionaires the ability to buy and sell elections,” said Sen. Sheldon Whitehouse, D-R.I., at a Capitol Hill news conference. Whitehouse was joined by Senate Rules Chairman Charles E. Schumer, D-N.Y., and by Democratic Sens. Michael Bennet of Colorado, Richard Blumenthal of Connecticut and Elizabeth Warren of Massachusetts.

Whitehouse’s reintroduction of the DISCLOSE Act coincides with a multi-pronged push by Democrats and their allies off Capitol Hill to score political points by attacking unrestricted, "secret" political money. Reid levels assaults virtually daily on the billionaire industrialists Charles and David Koch, who have helped underwrite tens of millions in political spending by conservative tax-exempt groups that don’t publicly report their donors.

Senate Democrats are also holding a series of hearings on undisclosed political money and on New Mexico Sen. Tom Udall’s proposal for a constitutional amendment, which would challenge a string of Supreme Court rulings, including the 2010 Citizens United v. FEC ruling to overturn limits on independent political spending.

Republicans have rejected Democrats’ proposed constitutional amendment as a blatant free speech violation, and have launched their own public relations campaign to equate campaign finance disclosure with political intimidation. Asked about allegations that disclosure invites harassment, Whitehouse scoffed that “someone who has the capacity to spend tens of millions of dollars in an election to get their way” need not be “worried about being taunted.”

But Democrats’ first version of the DISCLOSE Act, introduced in 2010, drew fire not just from conservatives but from liberal activists who complained that it would curb constitutionally protected lobbying activities. Democrats narrowed the bill considerably in 2012, and that more-limited version of the DISCLOSE Act was the one reintroduced today.

Asked about Democrats' own unrestricted political spending Tuesday, Whitehouse said "everyone should follow as much transparency as possible," but that Democrats can't "unilaterally disarm." He added that liberal outside spending might actually help spur GOP support for disclosure.

Democrats at the news conference displayed on a poster board a list of Republican senators who have endorsed disclosure in the past, including Sens. Lamar Alexander of Tennessee; John McCain of Arizona; Mitch McConnell of Kentucky, the Senate GOP leader; Lisa Murkowski of Alaska; and Jeff Sessions of Alabama. Whitehouse also quoted aloud several pro-transparency comments from Republicans, including McConnell.

But the likelihood that Democrats will win GOP support for either their constitutional amendment or the recently-reintroduced DISCLOSE Act remain virtually nil. Tuesday’s press conference came on the heels of yet another politically charged hearing in the GOP controlled House, at which Republicans continued their attacks on IRS officials for mishandling IRS attempts to curb political activities by non-disclosing tax-exempt groups.